World Superbike champion Colin Edwards is happy with the progress he is making with his new motorbike after his second test session.

Edwards chose not to defend his Superbike world title in order to contest the MotoGP Championship in 2003.

The Texan has been pleasantly surprised by the performance of the Aprilia RS Cube during testing at the Jerez circuit.

My first objective is to be comfortable with the bike Colin Edwards

"The power delivery of this bike is extraordinary," Edwards told www.motograndprix.com.

"Its smoothness has improved since our last visit to Jerez with the machine already adapting to my riding style.

"We are working at a good pace and the development is visible.

But Edwards has already identified areas where he can improve his lap times.

"After the first two days of tests, I can say that I have a four or five-tenths of a second margin I could improve," he said.

"But I haven't used it at the moment because I don't know the bike completely yet, and my first objective is to be comfortable with it."